Indicator-Transmitters

89. Positioning synchro transmitter 7 and pointers 88

traveling yoke 15, which has a total longitudinal

and 89 are geared to friction roller 60 and follow-up

motion of approximately 1.10 inches along the radius

motor 9. Long pointer 89 makes one complete

of friction disk 30. The yoke is positioned along the

revolution every 100 rpm, and short pointer 88 makes

disk radius by lead screw 16, which is driven by

one complete revolution for full-scale indication. The

follow-up motor 9.

relative direction of the speed is indicated by the

Friction roller 60, integral with helical gear 28,

backing signal indicator, which is lighted only when

drives helical gear 32, which is mounted on, but free

the propeller shaft rotates in the astern direction.

to turn through a limited range about, input shaft 42.

Running synchro receiver 8 is driven electrically

Thus, the helical gear rotates at a speed proportional

by the associated shaft transmitter at a speed exactly

to the distance between the position of the roller on

one-tenth that of the propeller shaft. The running

the disk and the center of the disk. The radius of

synchro drives the input shaft of the speed-measuring

contact at any given point will determine the drive

mechanism through gear 118. The speed-measuring

ratio and speed at which roller 60, and gears 28 and 32

mechanism converts the rotary motions into

will rotate.

proportional angular displacements, Running synchro

The speed of helical gear 32 is automatically

8 also drives revolution counter 141 through gears at

adjusted to match the speed of running synchro driven

a speed exactly one-tenth that of the propeller speed.

gear 118 by the slip ring and contact assembly 39, the

The revolution counter registers the total propeller

upper two slip rings of which are mounted on the hub

revolutions directly, irrespective of the direction of

of gear 32 and are free to turn through a limited range

rotation.

about input shaft 42. The assembly carries two outside

Positioning synchro transmitter 7 receives the

brush contacts, CW and CCW, each of which slides

angular displacement from the speed-measuring

on a slip ring. The center brush contact, C, slides on a

mechanism and transmits these displacements to the

slip ring, which is attached to hub 40 and is secured to

remotely located indicators.

input shaft 42 by friction thrust washer 54. The contact

assembly can be turned in either direction so that one

The speed-measuring mechanism operates on the

or the other of the outside contacts can mate with the

friction disk and roller assembly principle; that is, if a

center contact. This action energizes follow-up motor

disk is driven by a synchronous motor supplied with

9 and determines its direction of rotation.

a controlled frequency, the disk will run at a constant

speed irrespective of fluctuations of the ship's supply

When input gear 118 and helical gear 32 are

frequency. A roller placed in the center of the rotating

running at exactly the same speed, the contacts are

disk will not turn. However, if the roller is moved out

open, follow-up motor 9 is de-energized, and indicator

from the center of the disk, the roller will turn at a

pointers 88 and 89 are stationary. However, if the

speed that is proportional to the distance from the

speed of gear 118 changes, follow-up motor 9 is

center of the disk. For example, if the roller is moved

energized and drives lead screw 16, which moves yoke

out one-half inch from the center of the disk, the roller

15, in or out, depending on the direction of rotation, If

runs at twice the speed at which it ran when moved

the speed of gear 118 is faster than the original

one-fourth inch from the center of the disk. If the

balanced speed, the CW contacts close and, if the

position of the roller on the disk is varied, the speed

speed is lower, the CCW contacts close. The contacts

of the roller is varied in direct proportion to the

will remain closed to energize the follow-up motor in

distance the roller is positioned from the center of the

a correcting direction until the radius of disk contact

constmt-speed disk.

with roller 60 reaches a new value where the speed of

gear 32 is again equal to that of gear 118. At this point,

The friction disk and roller assembly also operates

the contacts open to de-energize the follow-up motor.

on the principle of comparing an unknown speed with

a known speed. The known speed in this case is

At zero (rpm) input from running synchro receiver

provided by synchronous motor 4, which drives

8, gear 118 is stationary and the contacts of the slip

friction disk 30 through gears at a constant speed. The

ring assembly will cause follow-up motor 9 to move

gearing is such that the disk speed is 16 2/3 rpm for

lead screw 16, forging friction roller 60 toward the

200 range units and 33 1/3 rpm for 400 range units.

center of friction disk 30. At the exact center, indicator

The friction disk is held in continuous contact with

pointers 88 and 89 should read zero rpm, and

friction roller 60, which is integral with helical gear

positioning synchro transmitter 7 should be on

28. The friction roller and helical gear are mounted on

electrical zero. However, the pointers will not reach

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